Commercial, emergency, military and passenger vehicles commonly employ direct current (DC) electrical systems operating at voltages of 12 volts or 24 volts DC. It is common for manufacturers to produce electrically driven subassemblies for each voltage range, e.g., a 12 volt product and a 24 volt product. A power supply for use with a known voltage source is typically simple and inexpensive. Alternatively, products designed for use with a wide range of voltages are provided with “switching” power supplies that transform the available voltage using known “buck”, “boost”, “sepic or “buck boost” topology circuit configurations. Switching power supplies are more complex and expensive than a simple DC power supply. Switching power supplies use high speed switching of a transistor and typically generate undesirable RF noise which then must be filtered or suppressed by shielding.
There is a need for a simple and inexpensive power supply circuit for motor vehicle electronic sub-assemblies that will allow the electronic sub-assembly to be used with both common motor vehicle voltage ranges.
There is a need for a simple and inexpensive power supply circuit for motor vehicle electronic subassemblies that does not generate RF noise.